Staphylococcus epidermidis biofilms: importance and implications

The coagulase-negative staphylococci and, in particular, Staphylococcus epi dermidis, have emerged as major nosocomial pathogens associated with infect ions of implanted medical devices. These organisms, which are among the mos t prevalent bacteria of the human skin and mucous membrane microflora, pres ent unique problems in the diagnosis and treatment of infections involving biofilm formation on implanted biomaterials. Epidemiological data that addr ess whether invasive S. epidermidis strains can be traced to commensal orga nisms or an endemic occurrence of distinct strains with enhanced virulence have important implications for the implementation of appropriate infection control measures. An extracellular polysaccharide adhesin represents a key virulence determinant in S. epidermidis and is required for biofilm format ion, Production of this adhesin, which is encoded by the ica operon, is sub ject to phase variable regulation (ON <----> OFF switching). Recent advance s in understanding the molecular events controlling polysaccharide adhesin synthesis and the potential clinical implications of its phase variable reg ulation are outlined. Further research in this area may contribute to the d evelopment of novel strategies for therapeutic intervention. Finally, in ad dition to antibiotic prophylaxis, preventive strategies to control S, epide rmidis medical device-related infections are focusing on the development of improved biomaterials and physical electrical barriers to impede bacterial colonisation.